Within a decade, the motion picture industry changed from a film-based to a digital workflow. The milestones of this transformation were the digital intermediate (DI) process, digital cinema, and eventually, digital acquisition. Initially, each of these changes was judged against the performance of film. The digital workflow preserves some of the characteristics of film, mostly the separation into scene-referred, log-encoded images (derived from film scans) and output-referred or rendered images (derived from the print film). Digital motion-picture cameras became successful when they captured enough dynamic range to implement a rendering with a soft highlight roll-off, which is a key feature of the cinematic film look. Nevertheless, the digital transformation has changed the color palette of movies.
There are differences between the colour gamut of print film and the gamut of a digital display. The P3 gamut of the reference digital cinema projectors is larger along the directions of the primary RGB colors while in the lower lightness region, print film can produce more saturated colours in the hue range from green to blue (200 < h* < 300). RGB laser cinema projectors and even more OLED displays with lower black levels and more saturated primary colors will extend the digital gamut to include more of these hues.
Principle differences remain on the capture side. Neither camera negative nor digital cameras are colorimetric observers, meaning there is no generally accurate transform from the captured or scanned signals to scene colorimetry estimates. Transforms optimized for the reproduction of important surface color stimuli may produce problematic results for monochromatic or almost monochromatic stimuli. This is a challenge for architectures that try to build a unified workflow for digital cameras from different manufacturers and film-based acquisition.
